Fast adaptive mode-conversion digital canceller

ABSTRACT

Transceivers and methods able to recover within less than 1 millisecond from quality degradation in the transceiver&#39;s operating point, including: receiving a signal from a second transceiver, using an adaptive digital equalizer and canceller (ADEC) to generate a slicer input signal, and generating slicing decisions and slicing errors that are used to adapt the ADEC. Shortly after identifying quality degradation in the transceiver&#39;s operating point, indicating the second transceiver to transmitting known data. And within less than 1 millisecond from identifying the quality degradation, the transceiver utilizes the known data to improve the accuracy of the slicing errors, which enables fast adaptation of the ADEC that improves the quality in the transceiver&#39;s operating point to a level that enables the transceiver to indicate the second transceiver to transmit data.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority of U.S. Provisional Application No.62/107,483, filed on 25 Jan. 2015.

BACKGROUND

Differential signaling is a method of transmitting information with twocomplementary signals on two conductors, such as paired wires.Differential signaling usually improves resistance to electromagneticinterference (EMI) since the information is conveyed through thedifference between the voltages on the wires. However, if there areimbalances or asymmetries between the two conductors, common modecomponents may arise even when the two conductors are differentiallydriven. The presence of common mode currents on a cable does notinherently degrade the integrity of differential signaling, but ifenergy can be transferred from a common mode to a differential mode,then the common mode current can become a dominant interference signal,in a phenomenon known as mode-conversion or mode coupling.

Mode conversion can cause significant performance degradation. Whileinternal interference sources (such as ISI, echo, FEXT, and NEXT) areknown to the link partners and can be cancelled effectively withcancellers and equalizers, the mode conversion interference is unknownuntil it occurs, and thus presents difficulties for the desiredperformance of high bandwidth communication systems.

SUMMARY

Transceivers and methods to recover within less than 1 millisecond fromquality degradation in a transceiver's operating point, including:receiving a signal from a second transceiver, feeding an adaptivedigital equalizer and canceller (ADEC) that generate a slicer inputsignal, generating slicing decisions and slicing errors and utilizingthem to adapt the ADEC. Shortly after identifying quality degradation inthe transceiver's operating point, indicating the second transceiver totransmitting known data. And within less than 1 millisecond fromidentifying the quality degradation, utilizing the known data to improvethe accuracy of the slicing errors, which enables fast adaptation of theADEC, that improves the quality in the transceiver's operating point toa level that enables the transceiver to indicate the second transceiverto transmit data.

BRIEF DESCRIPTION OF THE DRAWINGS

The embodiments are herein described, by way of example only, withreference to the accompanying drawings. In the drawings:

FIG. 1A illustrates one embodiment of a transceiver that converges fast;

FIG. 1B illustrates an alternative embodiment of a transceiver thatconverges fast;

FIG. 2A illustrates one embodiment of a communication system operatingover a differential communication channel that is not completely known;

FIG. 2A illustrates another embodiment of a communication systemoperating over a differential communication channel that is notcompletely known; and

FIG. 3 illustrates one embodiment of a communication system operatingover a differential communication channel.

DETAILED DESCRIPTION

FIG. 1A illustrates one embodiment of a transceiver that converges fast.Transceiver 100 (which does not includes the channel 201 and thetransceiver 102) includes the following elements: a common mode sensoranalog front end (CMS-AFE 710), a fast-adaptive mode-conversioncanceller (FA-MCC 712), a receiver analog front end (Rx AFE 716), anadaptive digital equalizer and canceller (ADEC 718), a slicer 735 (thatincludes a soft decision 730, a selector 732, and an error generator734), a Physical Coding Sublayer (PCS 740), a link layer 742, acontroller 752, a selector 750, a transmitter PCS (Tx PCS 760), atransmitter digital sampler (Tx dig samp 762), and a transmitter AFE (TxAFE 764).

The soft decision 730 decides on the reconstructed representation of theoriginal transmitted signal 728 by slicing the reconstructedrepresentation of the original transmitted signal 728. In oneembodiment, when a serious interference is too high, the ability of thesoft decision 730 to make an accurate decision may not be good enough,and/or the convergence time of the transceiver 100 may be too long.Thus, the controller 752 requests the transceiver 102 to transmit knowndata (such as to transmit the idle sequence, or a sequence based on theidle sequence), and configures the selector 732 to output the knowndecision received from the PCS 740 instead of the probably wrongdecision received from the soft decision 730. As a result of configuringthe selector 732 to output the known decision, the error generator 734is now able to generate the correct error based on the reconstructedrepresentation of the original transmitted signal 728 and the knowndecision 741 received from the PCS 740. The correct error enables theADEC 718 and FA-MCC 712 to converge fast because their convergence speedis function of the noisiness of the error, and thus receiving thecorrect error accelerates their convergence. Using the known decision741 also reduces the error propagation of the ADEC 718 because thecorrect decision is fed from selector 732 over line 719 to the ADEC 718.Therefore, having the correct error by injecting the known decision 741supports fast adaptation, reduces error propagation, and moves thetransceiver 100 into a stable state—also when the differentialcommunication channel suffers from a serious interference.

FIG. 1B illustrates an alternative embodiment of a transceiver thatconverges fast. Transceiver 101 does not include an FA-MCC component,although the ADEC 717 may include the functionality of the FA-MCC 712.Controller 753 may be similar to controller 752, which the differencethat controller 753 may be designed to operate without an FA-MCCcomponent.

In one embodiment, first and second transceivers forward time sensitivedata at a predetermined average rate and up to a predetermined packetdelay variation, includes:

An Rx analog front end (AFE) and a common mode sensor AFE (CMS-AFE) thatcouple the second transceiver to a differential communication channelcoupled to the first transceiver. The differential communication channelis not completely known, and the first and second transceivers areexpected to work at a first packet loss rate when there is no seriousinterference. From time to time the differential communication channelmay suffer from serious interferences that increase significantly thepacket loss rate to a second packet loss rate that is at least ten timesthe first packet loss rate.

The CMS-AFE extracts a digital representation of a common mode signal ofthe received differential signal, and forward it to a fast-adaptivemode-conversion canceller (FA-MCC) that generates a compensation signalto cancel the differential interference caused by mode-conversion of thecommon mode signal.

The FA-MCC utilizes large adaptation step size to cancel the effect ofthe serious interference fast.

The Rx AFE extracts the received differential signal and feeds it to anadaptive digital equalizer and canceller (ADEC). The ADEC includes oneor more equalizers, such as Decision Feedback Equalizer (DFE) and/orFeed-Forward Equalizer (FFE), and one or more cancellers, such as FEXTcanceller.

The FA-MCC and the ADEC reconstruct a representation of the originaltransmitted signal, and feed the representation of the originaltransmitted signal to a slicer that feeds a Physical Coding Sublayer(PCS) with sliced symbols. In one example, the original transmittedsignal is the signal sent from the first transceiver before shaping.

The PCS extracts a bitstream from the sliced symbols, and feeds a linklayer component that parses the sliced symbols into packets. It is notedthat bitstream includes bytestream and all other similar equivalents.

The link layer component comprises a retransmission module that:requests retransmission of packets with errors, and forwards the packetsin the correct order after receiving the retransmitted packets. It isnoted that packets with errors includes missing packets and any otherpacket that may require retransmission.

And the FA-MCC converges at a short time, such that the retransmissionscaused by the serious interference still enable the transceiver toforward packets at the predetermined average rate and within thepredetermined packet delay variation.

FIG. 2A illustrates one embodiment of a communication system operatingover a differential communication channel that is not completely knownand may suffer from serious common-mode-to-differential-modeinterference (in some cases may be shortly referred to as “seriousinterference”). The communication system includes a transceiver 201 anda transceiver 200 (which does not include the transceiver 201 and thechannel 210), capable of communicating at a high throughput, withcommunication rates possibly exceeding 120 Mbps, 1.2 Gbps, or 10 Gbps.

The communication system is implemented, at least in part, on IntegratedCircuits (ICs) having limited resources. The communication systemfurther implements a retransmission module on the ICs. In oneembodiment, the first transceiver utilizes a retransmission module 204that uses a buffer 205 to store packets that may have to beretransmitted. In one embodiment, the second transceiver utilizes aretransmission module 236 that uses a buffer 237 to store the receivedpackets until all the packets are received successfully, and then thebuffer may forward the received packets in the correct order to aclient. Additionally or alternatively, the retransmission module 236 mayuse the buffer 237 to store the received packets for a short perioduntil it is possible to forward them to the client, optionally in theorder of their arrival, which may not be the correct order.

The sizes of the buffers (205, 237) used by the retransmission modulemay be limited in order to save cost. In one example, the buffer 205 ofthe first transceiver can store up to 20 microseconds of traffic sent atthe highest communication rate. In another example, the secondtransceiver forwards the packets in the correct order and the buffer 237of the second transceiver can store up to 30 microseconds of trafficsent at the highest communication rate. In still another example, atleast one of the buffers used by the first and second transceiver canstore up to 100 microseconds of traffic sent at the highestcommunication rate.

Upon detecting a new serious interference, the second transceiverutilizes a fast-adaptive mode-conversion canceller (FA-MCC) to generatea compensation signal to cancel the differential interference caused bymode-conversion of the common mode signal. Optionally, until theinterference is cancelled, the first transceiver retransmits the lostpackets. The FA-MCC may not have in advanced information regarding theproperties of the interference, and thus the FA-MCC uses largeadaptation step size that enables fast convergence. Although the actualsize of the large adaptation step size depends on the specificimplementation, a person skilled in the art should be able to calculatethe values of the large adaptation step sizes to support convergencetime that is short enough for the communication system to meet itsdesign goals and/or real-time requirements. One example of a design goalis not to exceed the limited capacity of one or more of the buffers 205and 237 used by the retransmission module. One example of a real-timerequirement is not to exceed the maximum permitted delay allocated tothe communication channel.

As a result of the large adaptation step size, the convergence of theFA-MCC after a serious interference is usually not optimal.

In one example, the serious interference causes packet loss to exceed50% at the second transceiver, and the FA-MCC is designed to convergewithin less than 20 microseconds to a level that reduces the packet lossat the second transceiver to less than 5%. Optionally, packet loss iscalculated as the number of packet lost divided by the number of packetssent.

In another example, the serious interference causes packet loss toexceed 10% at the second transceiver, and the FA-MCC is designed toconverge within less than 10 microseconds to a level that reduces thepacket loss at the second transceiver to less than 1%.

In still another example, the serious interference causes packet loss toexceed 2% at the second transceiver, and the FA-MCC is designed toconverge within less than 20 microseconds to a level that reduces thepacket loss at the second transceiver to less than 0.1%.

In one embodiment, the communication channel is relatively short (forexample, shorter than 10 meters, or shorter than 3 meters) and thus isnot considered difficult. In such a channel, the communication systemcan operate well enough with the non-optimal convergence of the FA-MCCbecause the leftover interference that was not cancelled does notprevent successful communication over the channel.

The digital canceller 225 may be implemented in various ways. FIG. 2Aillustrates one example in which the digital canceller 225 includes atleast an equalizer 224 and a Decision Based Filter (DBF) 228. In oneexample, equalizer 224 may be a Feed Forward Equalizer (FFE).

The term “Decision Based Filter”, such as DBF 228, refers to a filterfed at least by a slicer's output, such as slicing results and/orslicing errors. In one example, the DBF includes a non-adaptive DecisionFeedback Equalizer (DFE), or a non-adaptive FEXT canceller, fed by theslicing results. In another example, the DBF includes an adaptive DFE,or an adaptive FEXT canceller, fed by the slicing results and/or theslicing errors. In still another example, the DBF includes an adaptiveFeed-Forward Equalizer (FFE) fed by the slicing errors for adaptationpurpose.

The term “slicer” or “slicer function”, such as slicer 226, is definedas a one or more dimensional quantizer that outputs the quantizationresult. Optionally, the slicer may include different slicers fordifferent modulations. Optionally, the slicer may output one or more ofthe following indications: the error between the received signal and thequantization result, the slicer function used for producing the slicingresult, the direction of the slicing error, and/or other indications.

The slicing results are fed to a Physical Coding Sublayer (PCS), such asPCS 234, which parses the data packets and extracts information such asa packet header, a packet payload, a packet tail, and/or an errordetection code. It is noted that herein an “error detection code” alsocovers an “error correction code”.

In one embodiment, the retransmission module 236 receives the parsedpackets from the PCS 234, and based on the received parsed packets itmay request retransmission of the packets with errors. In oneembodiment, one of the relationships between the FA-MCC and theretransmission module 236 is that the buffer 237 is large enough tobuffer packets that are received until the FA-MCC cancels the effect ofthe serious interference. The combination of the FA-MCC and theretransmission module 236 enables the system to use small retransmissionbuffers also when operating over a communication channel that is notcompletely known and suffers from seriouscommon-mode-to-differential-mode interference.

FIG. 2B illustrates one embodiment of a communication system operatingover a differential communication channel that is not completely knownand may suffer from serious common-mode-to-differential-modeinterference. The communication system includes a transceiver 262 and atransceiver 260 (which does not include the transceiver 262 and thechannel 210), capable of communicating at a high throughput, withcommunication rates possibly exceeding 100 Mbps, 1 Gbps, or 10 Gbps.

The transceiver 260 is implemented on an integrated circuit (IC) havinglimited resources. The transceiver 260 includes at least first andsecond AFEs (222, 230) coupled to the transceiver 262 over adifferential communication channel 210 that is not completely known;from time to time the differential communication channel may suffer fromserious interferences that prevent normal operation.

The CMS-AFE extracts a digital representation of a common mode signal ofthe received differential signal, and forwards it to a fast-adaptivemode-conversion canceller (FA-MCC) that generates a compensation signalto cancel the differential interference caused by mode-conversion of thecommon mode signal. The FA-MCC utilizes large adaptation step size tocancel the effect of the serious interference fast. The large adaptationstep size enables it to cancel, within less than 20 microseconds, theeffect of the serious common-mode-to-differential-mode interference to alevel that enables the normal operation. The digital canceller 225 feedsa slicer 226 that feeds a PCS 234 with quantization results. The PCS 234extracts packet data from the quantization results and drives aretransmission module 270 that requests retransmission of the packetswith errors based on the packet data. In one embodiment, theretransmission module is limited to support retransmission of up to 200%of the packets received during the time it takes the FA-MCC to cancelthe effect of the serious interference.

In one embodiment, the retransmission module 270 is implemented on theIC with limited resources that cannot support retransmission of morethan 200% of the packets received during the time it takes the FA-MCC tocancel the effect of the serious interference. In one embodiment, theretransmission module includes a retransmission buffer 271 able to storeup to 200% of the packets received during the time it takes the FA-MCCto cancel the effect of the serious interference. In one embodiment, theretransmission module 270 is limited to support retransmission of up to200% of the packets received during the time it takes the FA-MCC tocancel the effect of the serious interference in order to achieve one ormore of the following requirements: a maximum allowed jitter, a maximumamount of dropped packets, and requirements related to time sensitivedata transmitted over the communication channel.

In one example, the retransmission module further comprises a bufferthat stores the received packets until all packets are receivedsuccessfully. Additionally or alternatively, the size of the buffer islimited to store the amount of packets that are received during up to 20microseconds of normal operation. Additionally or alternatively, theretransmission module further comprises a buffer that stores thereceived packets until they are requested by a client.

In one example, the packet data comprises information related to apacket header, a packet payload, a packet tail, and/or an errordetection code. Additionally or alternatively, the FA-MCC may not beconfigured to converge optimally, and as such may not reach an optimalsolution even after 1 second. Additionally or alternatively, the digitalcanceller may include an equalizer and a Decision Based Filter (DBF).Additionally or alternatively, the equalizer may be a Feed ForwardEqualizer (FFE). Additionally or alternatively, the DBF may be a filterfed by an output of the slicer.

In some embodiments, upon detecting a serious interference, thecommunication system reduces the code rate until the FA-MCC cancels theeffect of the serious interference. After the FA-MCC cancels the effectof the serious interference, the communication system increases the coderate, optionally until returning to the code rate used before theserious interference was detected.

Reducing the code rate improves the packets' robustness to noise, andthus enables the transceiver to receive at least some of the packetssuccessfully. Reducing the code rate may be implemented in addition tothe retransmission module described above.

The code rate may be reduced by various techniques such as DynamicModulation Coding (DMC), adding Error Correction Code (ECC), and/ortransmitting a known sequence (that reduces the code rate to practicallyzero).

In one embodiment, the code rate is reduced by decreasing the modulationorder using Dynamic Modulation Coding (DMC). DMC is described, forexample, in U.S. Pat. No. 8,565,337, titled “Devices for transmittingdigital video and data over the same wires”, which is incorporatedherein by reference in its entirety. For example, upon detecting aserious interference, a Pulse-Amplitude Modulation (PAM) transceiver mayswitch from using PAM16 to PAM4 until the FA-MCC cancels the effect ofthe serious interference, and then switch from PAM4 to PAM8, and fromPAM8 back to PAM16 when the channel properties allow.

In another embodiment, the code rate is reduced by adding ECC, either byadding ECC when there was no ECC, or by increasing the amount of the ECCoverhead in order to improve the Signal to Noise Ratio (SNR). Forexample, the ECC may be added by continually adding ECC overhead to thestream, optionally in a similar manner to convolutional codes.Additionally or alternatively, the ECC may be added/strengthened byadding the EC overhead to fixed length data segment, optionally in asimilar manner to block codes.

In another embodiment, the code rate is reduced to practically zero bytransmitting a known sequence. In one example, the known sequence isbased on the scrambler sequence, such as transmitting the scrambler, ortransmitting bitwise complement code words of the scrambler. In anotherexample, the known sequence is based on the idle sequence, such astransmitting the idle sequence, or transmitting bitwise complement codewords of the idle sequence. One embodiment of a transmitter thattransmits bitwise complement code words of the idle sequence includes anencoder configured to encode a first frame, a basic idle sequence, and asecond frame, wherein the first frame, the basic idle sequence, and thesecond frame include code words. The transmitter further includes anidle sequence modifier configured to produce an idle sequence byreplacing certain M code words of the basic idle sequence with M bitwisecomplement code words (where, optionally, each bitwise complement codeword appears in the basic idle sequence). Bitwise complement, also knownas bitwise NOT, applies logical negation on each bit, forming the ones'complement of a given binary value. For unsigned integers, the bitwisecomplement of a number is the mirror reflection of the number acrossessentially the half-way point of the unsigned integer's range.

FIG. 3 illustrates one embodiment of a communication system operatingover a differential communication channel 310 that is not completelyknown and may suffer from serious common-mode-to-differential-modeinterference. The communication system includes a transceiver 301 and atransceiver 300 (which does not include the transceiver 301 and thechannel 310) capable of communicating at a high throughput, withcommunication rates possibly exceeding 100 Mbps, 1 Gbps, or 10 Gbps.

The communication system may be implemented, at least in part, onIntegrated Circuits (ICs) having limited resources. In one embodiment,the transceiver 301 utilizes a retransmission module 304 that uses abuffer 305 to store the packets that may have to be retransmitted. Inone embodiment, the transceiver 300 utilizes a retransmission module 342that uses a buffer 343 to store the received packets until all thepackets are received successfully.

In one embodiment, the sizes of the buffers (305, 343) used by theretransmission modules may be limited in order to save cost. In oneexample, the buffer 305 of the transceiver 301 can store up to 20microseconds of traffic sent at the highest communication rate. Inanother example, the transceiver 300 forwards the packets in the correctorder and the buffer 343 of the transceiver 300 can store up to 30microseconds of traffic sent at the highest communication rate. In stillanother example, at least one of the buffers of the transceiver 301 andtransceiver 300 can store up to 100 microseconds of traffic sent at thehighest communication rate.

Upon detecting a new serious interference, the transceiver 300 utilizesthe FA-MCC with large adaptation step size to cancel the effect of theserious interference fast. Until the interference is cancelled, the ratecontroller 346 reduces the rate of transmitting the packets in order toimprove the packets' robustness to noise.

In response to receiving an indication from the PCS 340 about theserious interference, the rate controller 346 commands the transceiver301 to reduce its code rate, and updates the transceiver 300 about thereduction in the code rate. In response to receiving a furtherindication from the PCS 340 that the FA-MCC successfully canceled theeffect of the serious interference, the rate controller 346 commands thetransceiver 301 to increase its code rate, and updates the transceiver300 about the increment in the code rate.

The indication from the PCS 340 to the rate controller 346 may byfunction of one or more of the following values: the percent of the lostpackets, the rate of the lost packets, a function of the lost andsuccessfully received packets, a score proportional to the detectedinterference, a score proportional to a slicing error provided by theslicer 326, and/or a score proportional to the number of errors detectedby the PCS 340.

In one example, the command from the rate controller 346 to thetransceiver 300 about the reduction in the code rate causes the slicer326 to change its slicer function to a slicing function suitable for thereduced code rate.

Upon detecting that the effect of the serious interference has beencancelled by the FA-MCC, the rate controller 346 increases the code rateof transmitting the packets.

In one embodiment, at least one of the packets that could not been sentdue to insufficient bandwidth while the code rate was reduced, isdiscarded without attempting a delayed transmission or retransmission.In one example, the traffic transmitted over the communication channel310 includes video pixel data that is discarded during the time thesystems uses the lower code rate.

In another embodiment, at least some of the packets that could not besent while the code rate was reduced, are stored, optionally in buffer305 at the transceiver 301, and transmitted after the code rate isrestored to a level that permits transmission of the extra data. In oneexample, the traffic transmitted over the communication channel 310includes time sensitive data (e.g., video synchronization data) and timeinsensitive data (e.g., Ethernet data). While operating in the lowercode rate, the system continues to transmit the time sensitive data, andstores the time insensitive data optionally in buffer 305. Aftercancelling the interference and restoring the code rate to a levelhaving higher bandwidth, the system transmits the stored timeinsensitive data in parallel to transmission of ongoing data.

In one example, the command from the rate controller 346 to thetransceiver 300 about increasing the code rate causes the slicer 326 tochange its slicer function to one suitable for the higher code rate.

The convergence of the FA-MCC after serious interference is usually notoptimal because an optimal convergence is usually not fast enough.

In one example, the serious interference causes packet loss to exceed50% at the transceiver 300, and the FA-MCC is designed to convergewithin less than 20 microseconds to a level that reduces the packet lossat the transceiver 300 to less than 5%.

In another example, the serious interference causes packet loss toexceed 10% at the transceiver 300, and the FA-MCC is designed toconverge within less than 10 microseconds to a level that reduces thepacket loss at the transceiver 300 to less than 1%.

In still another example, the serious interference causes packet loss toexceed 2% at the transceiver 300, and the FA-MCC is designed to convergewithin less than 20 microseconds to a level that reduces the packet lossat the transceiver 300 to less than 0.1%.

The digital canceller 325 may be implemented in various ways. FIG. 3illustrates one example in which the digital canceller 325 includes atleast an equalizer 324 and a DBF 328. In one example, the equalizer 324and/or the DBF 328 may have different functions for the different datarates.

Using different function for different data rates is described, forexample, in U.S. Pat. No. 8,930,795, titled “Methods for slicingdynamically modulated symbols”, which is incorporated herein byreference in its entirety. For example, the slicing results are fed tothe PCS 340, which parses the data packets and extracts information suchas a packet header, a packet payload, a packet tail, and packetmodulation information. The PCS 340 determines the modulation used bythe transceiver 301, and indicates the slicer 236 of which slicingfunction to use. The slicer 326 may then provide the slicing resultsfrom the indicated slicer to the DBF 328. Optionally, the slicer 326 mayadditionally provide slicing errors associated with the slicing results.Following that, the DBF 328 generates the appropriate output and adds itto the incoming signal from the equalizer 324.

In one embodiment, the transceiver 300 includes an optionalretransmission module 342 that receives the parsed packets from the PCS340, and based on the received parsed packets it may requestretransmission of the packets with errors. In one embodiment, one of therelationships between the FA-MCC and the retransmission module 342 isthat the buffer 343 used by the retransmission module 342 is largeenough to store the arriving packets until the FA-MCC cancels the effectof the serious interference. The combination of the fast convergingFA-MCC and the retransmission module 342 enables both transceivers 300and 301 to use small retransmission buffers also when operating over acommunication channel that is not completely known and suffers fromserious common-mode-to-differential-mode interference.

As a result of reducing the code rate, some of the packets may not betransmitted even once because the effective communication bandwidth isreduced. These packets may be stored in the retransmission buffer 305 atthe transceiver 301, which has to be large enough to store the packetsthat cannot be transmitted as long as the system operates at the lowercode rate (typically until the effect of the seriouscommon-mode-to-differential-mode interference is cancelled to asufficient level).

The following four embodiments summarize certain non-limiting aspects ofthe inventions:

Embodiment #1: A transceiver configured to recover within less than 1millisecond from quality degradation in its operating point, comprising:a receiver analog front end (Rx AFE), an adaptive module comprising atleast one of an adaptive digital equalizer and an adaptive digitalcanceller (ADEC), and a slicer; the Rx AFE receives a signal of morethan 500 Mbps from a second transceiver over a link, and feeds thesignal to the ADEC that generates a slicer input signal; the slicerutilizes the slicer input signal to generate slicing decisions andslicing errors; wherein the slicing errors are used to adapt the ADEC;shortly after identifying quality degradation in the transceiver'soperating point, the transceiver indicates the second transceiver totransmitting known data; and within less than 1 millisecond fromidentifying the quality degradation, the transceiver utilizes the knowndata to improve the accuracy of the slicing errors, which enables fastadaptation of the ADEC, that improves the quality in the transceiver'soperating point to a level that enables the transceiver to indicate thesecond transceiver to transmit data. wherein the quality degradation inthe transceiver's operating point is quality degradation in the slicerinput signal, which causes errors in slicing decisions above apredetermined threshold.

Referring to the embodiment above, optionally, the quality degradationin the transceiver's operating point is quality degradation in theslicing errors, which are indicative of the detection quality of thetransceiver. Optionally, the quality degradation in the transceiver'soperating point comprises identifying amount of CRC errors above apredetermined threshold. Optionally, within less than 100 microsecondsfrom identifying the quality degradation, the transceiver utilizes theknown data to improve quality in its operating point to a level thatenables the transceiver indicate the second transceiver to transmitdata. Optionally, the link maintains a fixed rate of data transmission,such that there is less than 2% difference between a first amount ofunique data successfully transmitted over the link over a first2-millisecond window that ends 100 microseconds before identifying thequality degradation and a second amount of unique data successfullytransmitted over the link over a second 2-millisecond window adjacent tothe first window. Optionally, the link maintains a fixed rate of datatransmission, such that there is less than 1% difference between a firstamount of unique data successfully transmitted over the link over afirst 500 microseconds window that ends 50 microseconds beforeidentifying the quality degradation and a second amount of unique datasuccessfully transmitted over the link over a second 500 microsecondswindow adjacent to the first window. Optionally, the quality degradationwould have caused a difference above 10% between the amounts of uniquedata successfully transmitted over the two adjacent 500 microsecondswindows had the transceiver not been recovered from the qualitydegradation in its operating point. Optionally, the transceiver furtherutilizes retransmission to recover the packets that were lost from thetime of the quality degradation in the operating point until the time ofrecovery. Optionally, using the known data enables the slicer tocalculate the correct slicing errors based on the correct slicingdecisions received from the PCS. Optionally, the transceiver utilizesthe known data to improve quality in its operating point by utilizingthe known data to improve the accuracies of the slicing decisions andthe slicing errors, which are used to adapt the ADEC. Optionally, theADEC comprises one or more equalizers selected from: Decision FeedbackEqualizer (DFE) and Feed-Forward Equalizer (FFE), and one or morecancellers selected from: FEXT canceller, NEXT canceller, and DFEcanceller. Optionally, the ADEC comprises an Adaptive Decision FeedbackEqualizer (ADFE) with more than 50 taps, whereby the better the slicingdecisions the lower the ADFE's error propagation. Optionally, thetransceiver further utilizes a Physical Coding Sublayer (PCS) thatextracts a bitstream from the slicing decisions, and feeds the bitstreamto a link layer component that parses the bitstream into packets.Optionally, the link is a differential wired communication link.Optionally, the transceiver indicates the second transceiver to increasethe rate according to the quality in transceiver's operating point.Optionally, the FA-MCC comprises an adaptive equalizer, and the moreaccurate the slicing errors the faster the convergence of the FA-MCC.

Embodiment #2: A method for recovering within less than 1 millisecondfrom quality degradation in a transceiver's operating point, comprising:receiving, by the transceiver, a signal of more than 500 Mbps from asecond transceiver over a link; feeding the signal to an adaptive modulecomprising at least one of an adaptive digital equalizer and an adaptivedigital canceller (ADEC), for generating a slicer input signal;utilizing the slicer input signal to generate slicing decisions andslicing errors; utilizing the slicing errors for adapting the ADEC;shortly after identifying quality degradation in the transceiver'soperating point, indicating the second transceiver to transmitting knowndata; and within less than 1 millisecond from identifying the qualitydegradation, utilizing the known data to improve the accuracy of theslicing errors, which enables fast adaptation of the ADEC, that improvesthe quality in the transceiver's operating point to a level that enablesthe transceiver to indicate the second transceiver to transmit data.

Referring to the embodiment above, optionally, within less than 100microseconds from identifying the quality degradation, furthercomprising utilizing the known data to improve the quality in theoperating point to a level that enables the transceiver indicate thesecond transceiver to transmit data. Optionally, the link maintains afixed rate of data transmission, such that there is less than 2%difference between a first amount of unique data successfullytransmitted over the link over a first 2-millisecond window that ends100 microseconds before identifying the quality degradation and a secondamount of unique data successfully transmitted over the link over asecond 2-millisecond window adjacent to the first window. Optionally,the link maintains a fixed rate of data transmission, such that there isless than 1% difference between a first amount of unique datasuccessfully transmitted over the link over a first 500 microsecondswindow that ends 50 microseconds before identifying the qualitydegradation and a second amount of unique data successfully transmittedover the link over a second 500 microseconds window adjacent to thefirst window. Optionally, the method further utilizes retransmission torecover the packets that were lost from the time of the qualitydegradation in the operating point until the time of recovery.

Embodiment #3: A transceiver configured to recover within less than 1millisecond from quality degradation in its operating point, comprising:a receiver analog front end (Rx AFE), an adaptive module comprising atleast one of an adaptive digital equalizer and an adaptive digitalcanceller (ADEC), a common mode sensor AFE (CMS-AFE), a fast-adaptivemode-conversion canceller (FA-MCC), and a slicer; the Rx AFE receives asignal of more than 500 Mbps from a second transceiver over adifferential wired communication link, and feeds the ADEC that generatesan equalized signal; the CMS-AFE senses the common mode signal of thedifferential wired communication link and feeds the FA-MCC thatgenerates a compensation signal; wherein the compensation signal isindicative of differential interference caused by mode-conversion of acommon mode signal; the slicer utilizes the equalized signal and thecompensation signal to generate slicing decisions and slicing errors;wherein the slicing errors are used to adapt the ADEC and the FA-MCC;shortly after identifying quality degradation in the transceiver'soperating point, the transceiver indicates the second transceiver toreduce the rate of the transmitted data in order to improves detectionrate at the transceiver; and within less than 1 millisecond fromidentifying the quality degradation, the transceiver utilizes theimproved detection rate to improve the accuracy of the slicing errors,which enables fast adaptation of the ADEC, that improves the quality inthe transceiver's operating point to a level that enables thetransceiver to indicate the second transceiver to increase the rate.

Referring to the embodiment above, optionally, the identified qualitydegradation in the slicer input signal causes errors in slicingdecisions above a predetermined threshold. Optionally, the FA-MCC isimplemented as part of the ADEC. Optionally, the transceiver furtherutilizes the slicing decisions to adapt the ADEC and the FA-MCC.Optionally, the quality degradation in the transceiver's operating pointis quality degradation in the slicer input signal, which causes errorsin slicing decisions above a predetermined threshold. Optionally, thequality degradation in the transceiver's operating point is qualitydegradation in the slicing errors, which are indicative of the detectionquality of the transceiver. Optionally, the quality degradation in thetransceiver's operating point comprises identifying amount of CRC errorsabove a predetermined threshold. Optionally, within less than 100microseconds from identifying the quality degradation, the transceiverutilizes the known data to improve quality in its operating point to alevel that enables the transceiver indicate the second transceiver totransmit data. Optionally, the link maintains a fixed rate of datatransmission, such that there is less than 2% difference between a firstamount of unique data successfully transmitted over the link over afirst 2-millisecond window that ends 100 microseconds before identifyingthe quality degradation and a second amount of unique data successfullytransmitted over the link over a second 2-millisecond window adjacent tothe first window. Optionally, the link maintains a fixed rate of datatransmission, such that there is less than 1% difference between a firstamount of unique data successfully transmitted over the link over afirst 500 microseconds window that ends 50 microseconds beforeidentifying the quality degradation and a second amount of unique datasuccessfully transmitted over the link over a second 500 microsecondswindow adjacent to the first window. Optionally, the quality degradationwould have caused a difference above 10% between the amounts of uniquedata successfully transmitted over the two adjacent 500 microsecondswindows had the transceiver not been recovered from the qualitydegradation in its operating point. Optionally, the transceiver furtherutilizes retransmission to recover the packets that were lost from thetime of the quality degradation in the operating point until the time ofrecovery. Optionally, using the known data enables the slicer tocalculate the correct slicing errors based on the correct slicingdecisions received from the PCS. Optionally, the transceiver utilizesthe known data to improve quality in its operating point by utilizingthe known data to improve the accuracies of the slicing decisions andthe slicing errors, which are used to adapt the ADEC. Optionally, theADEC comprises one or more equalizers selected from: Decision FeedbackEqualizer (DFE) and Feed-Forward Equalizer (FFE), and one or morecancellers selected from: FEXT canceller, NEXT canceller, and DFEcanceller. Optionally, the ADEC comprises an Adaptive Decision FeedbackEqualizer (ADFE) with more than 50 taps, whereby the better the slicingdecisions the lower the ADFE's error propagation. Optionally, thetransceiver further utilizes a Physical Coding Sublayer (PCS) configuredto extract a bitstream from the slicing decisions, and to feeds thebitstream to a link layer component that parses the bitstream intopackets. Optionally, the link is a differential wired communicationlink. Optionally, the transceiver indicates the second transceiver toincrease the rate according to the quality in transceiver's operatingpoint. Optionally, the FA-MCC comprises an adaptive equalizer, and themore accurate the slicing errors the faster the convergence of theFA-MCC.

Embodiment #4: A method for recovering within less than 1 millisecondfrom quality degradation in a transceiver's operating point, comprising:a receiver analog front end (Rx AFE), an adaptive module comprising atleast one of an adaptive digital equalizer and an adaptive digitalcanceller (ADEC), a common mode sensor AFE (CMS-AFE), a fast-adaptivemode-conversion canceller (FA-MCC), and a slicer; receiving, by thetransceiver, a signal of more than 500 Mbps from a second transceiverover a differential wired communication link; feeding the signal to anadaptive module comprising at least one of an adaptive digital equalizerand an adaptive digital canceller (ADEC), for generating a slicer inputsignal; sensing the common mode signal of the differential wiredcommunication link; feeing the sensed signal to a fast-adaptivemode-conversion canceller (FA-MCC) that generates a compensation signal;wherein the compensation signal is indicative of differentialinterference caused by mode-conversion of a common mode signal;utilizing the equalized signal and the compensation signal forgenerating slicing decisions and slicing errors; utilizing the slicingerrors for adapting the ADEC and the FA-MCC; shortly after identifyingquality degradation in the transceiver's operating point, indicating thesecond transceiver to reduce the rate of the transmitted data in orderto improves detection rate at the transceiver; and within less than 1millisecond from identifying the quality degradation, utilizing theimproved detection rate to improve the accuracy of the slicing errors,which enables fast adaptation of the ADEC, that improves the quality inthe transceiver's operating point to a level that enables thetransceiver to indicate the second transceiver to increase the rate.

Referring to the embodiment above, optionally, within less than 100microseconds from identifying the quality degradation, furthercomprising utilizing the known data to improve the quality in theoperating point to a level that enables the transceiver indicate thesecond transceiver to transmit data. Optionally, the link maintains afixed rate of data transmission, such that there is less than 2%difference between a first amount of unique data successfullytransmitted over the link over a first 2-millisecond window that ends100 microseconds before identifying the quality degradation and a secondamount of unique data successfully transmitted over the link over asecond 2-millisecond window adjacent to the first window. Optionally,the link maintains a fixed rate of data transmission, such that there isless than 1% difference between a first amount of unique datasuccessfully transmitted over the link over a first 500 microsecondswindow that ends 50 microseconds before identifying the qualitydegradation and a second amount of unique data successfully transmittedover the link over a second 500 microseconds window adjacent to thefirst window. Optionally, the method further utilizes retransmission torecover the packets that were lost from the time of the qualitydegradation in the operating point until the time of recovery.

Certain elements of the following additional optional embodiments may becombined with the above described embodiments. The following embodimentsare independent of the above described embodiments and are not intendedto limit the above described embodiments in any way.

In one embodiment, a transceiver that recovers fast from a seriousinterference, includes: a first transceiver that communicates with asecond transceiver over a link; the first transceiver comprises: areceiver analog front end (Rx AFE), an adaptive digital equalizer andcanceller (ADEC), a slicer, a Physical Coding Sublayer (PCS), and linklayer component; the Rx AFE receives a signal from the secondtransceiver and feeds the signal to the ADEC that feeds an equalizedsignal to the slicer that generates slicing decisions and slicingerrors; the slicer decisions and the slicer errors are used to adapt theADEC that generates the equalized signal; optionally, the ADEC comprisesan Adaptive Decision Feedback Equalizer (ADFE) with more than 50 taps,the better the slicer decisions the lower the ADFE's error propagation,and the smaller the slicer errors the faster the ADFE's convergence; thePCS extracts a bitstream from the slicing decisions, and feeds thebitstream to the link layer component that parses the bitstream intopackets; shortly after identifying a serious interference that causes anerror above a predetermined threshold, the first transceiver indicatesthe second transceiver to transmit known data, the PCS utilizes theknown data to provide correct decisions to the slicer, and the slicercalculates correct slicer errors based on the correct decisions and theequalized signal; and shortly after the ADFE eliminates the errorpropagation fast as a result of the correct decisions, and convergesfast as a result of the correct slicer errors, the first transceiverindicates the second transceiver to transmit unknown data.

In one embodiment, a transceiver that recovers fast from a seriousinterference, includes: a first transceiver that communicates with asecond transceiver over a differential wired communication channel; thefirst transceiver comprises: a receiver analog front end (Rx AFE), anadaptive digital equalizer and canceller (ADEC), a common mode sensorAFE (CMS-AFE), a fast-adaptive mode-conversion canceller (FA-MCC), aslicer, a Physical Coding Sublayer (PCS), and link layer component; theRx AFE receives a signal from the second transceiver; the Rx AFE feedsthe signal to the ADEC that generates an equalized signal; the CMS-AFEfeeds an indication of the common mode to differential mode interferenceto the FA-MCC that generates a compensation signal to cancel adifferential interference caused by mode-conversion of a common modesignal; the slicer generates slicing decisions and slicing errors basedon the equalized signal and the compensation signal; the ADEC is adaptedbased on the slicer errors, and optionally also based on the slicerdecisions; optionally, the ADEC comprises an Adaptive Decision FeedbackEqualizer (ADFE) with more than 50 taps, the better the slicer decisionsthe lower the ADFE's error propagation, and the smaller the slicererrors the faster the ADFE's convergence; the FA-MCC is adapted based onthe slicer errors, wherein the more accurate the slicer error is, thefaster the FA-MCC converges; the PCS extracts a bitstream from theslicing decision, and feeds the bitstream to the link layer componentthat parses the bitstream into packets; shortly after identifying aserious interference that causes an error above a predeterminedthreshold, the first transceiver accelerates its adaptation to theserious interference by indicating the second transceiver to reduce therate of the transmitted data; whereby the reduced rate improves theaccuracies of both the slicer decisions and the slicer errors; andshortly after the ADFE reduces the error propagation fast as a result ofthe more accurate slicer decisions, and converges fast as a result ofthe better accuracy of the slicer errors, the first transceiverindicates the second transceiver to increase the rate of the transmitteddata.

Referring to the embodiment above, optionally, the analyzing of thereceived signal comprises at least one of the following: extracting apacket from the received signal and identifying a CRC errors in thepacket, identifying a slicing error above a predetermined threshold,identifying that the received signal is not an idle sequence on idletime, and receiving an indication of a serious interference from acommon mode detector. In some example, detecting the seriousinterference based on the slicer error can lead to a very fast detectionof the serious interference, even after just a few symbols, andespecially when using a low modulation where the symbols are expected tobe close to the decision levels of the slicer. Optionally, the detectionmodule identifies the serious interference within less than 10microseconds after the serious interference reaches a predeterminedthreshold. Optionally, the detection module identifies the seriousinterference within less than 1 microsecond after the seriousinterference reaches a predetermined threshold. Optionally, thetransceiver receives the signal from a wired link, and it is assumedthat the link parameters do not change during the time of the commonmode interference.

In one embodiment, communication link comprising first and secondtransceivers that communicate time sensitive data over a link, includes:an Rx analog front end (AFE) and a common mode sensor AFE (CMS-AFE)coupled to a differential communication channel that is coupled to asecond transceiver; the differential communication channel is notcompletely known, and the transceiver is expected to work at a firstpacket loss rate when there is no serious interference; from time totime the differential communication channel suffers from seriousinterference that increases the packet loss rate of the transceiver to asecond packet loss rate that is at least ten times the first packet lossrate; the CMS-AFE extracts a digital representation of a common modesignal of the received differential signal, and forwards it to afast-adaptive mode-conversion canceller (FA-MCC) that generates acompensation signal to cancel the differential interference caused bymode-conversion of the common mode signal; responsive to receiving anindication that the serious interference has occurred, the FA-MCCincreases its adaptation step size (ASS) by at least 50% in order tocancel the effect of the serious interference fast; the Rx AFE extractsthe received differential signal and feeds it to an adaptive digitalequalizer and canceller (ADEC); the FA-MCC and the ADEC reconstruct arepresentation of the original transmitted signal, and feed therepresentation of the original transmitted signal to a slicer that feedsa Physical Coding Sublayer (PCS) with sliced symbols; the PCS extracts abitstream from the sliced symbols, and feeds a link layer component thatparses the sliced symbols into packets; the link layer componentcomprises a retransmission module that requests retransmission ofpackets with errors; wherein the FA-MCC converges at a short time suchthat the retransmissions caused by the serious interference stillenables the transceiver to forward packets at the predetermined averagerate and in the correct order after receiving the retransmitted packets;and the FA-MCC reduces its ASS after it cancels the effect of theserious interference.

Referring to the embodiment above, optionally, the FA-MCC converges at ashort time such that the retransmissions caused by the seriousinterference still enables the transceiver to forward packets within apacket delay variation selected from the group of less than: 1millisecond, 200 microseconds, and 50 microseconds.

In one embodiment, a transceiver that forwards time sensitive data at apredetermined average rate, comprises: a receiver analog front end (RxAFE) and a common mode sensor AFE (CMS-AFE) coupled to a differentialcommunication channel that is coupled to a second transceiver; thedifferential communication channel is not completely known, and thetransceiver is expected to work at a first packet loss rate when thereis no serious interference; from time to time the differentialcommunication channel suffers from serious interference that increasesthe packet loss rate of the transceiver to a second packet loss ratethat is at least ten times the first packet loss rate; the CMS-AFEextracts a digital representation of a common mode signal of thereceived differential signal, and forwards it to a fast-adaptivemode-conversion canceller (FA-MCC) that generates a compensation signalto cancel the differential interference caused by mode-conversion of thecommon mode signal; responsive to receiving an indication that theserious interference has occurred, the FA-MCC increases its adaptationstep size (ASS) by at least 50% in order to cancel the effect of theserious interference fast; the Rx AFE extracts the received differentialsignal and feed it to an adaptive digital equalizer and canceller(ADEC); the FA-MCC and the ADEC reconstruct a representation of theoriginal transmitted signal, and feed the representation of the originaltransmitted signal to a slicer that feeds a Physical Coding Sublayer(PCS) with sliced symbols; the PCS extracts a bitstream from the slicedsymbols, and feeds a link layer component that parses the sliced symbolsinto packets; the link layer component comprises a retransmission modulethat requests retransmission of packets with errors; wherein the FA-MCCconverges at a short time such that the retransmissions caused by theserious interference still enables the transceiver to forward packets atthe predetermined average rate and in the correct order after receivingthe retransmitted packets; and the FA-MCC reduces its ASSafter itcancels the effect of the serious interference.

Referring to the embodiment above, in one example, the FA-MCC increasesits ASSby at least 200% in order to cancel the effect of the seriousinterference fast. In another example, the FA-MCC increases its ASSby atleast 1000% in order to cancel the effect of the serious interferencefast. Optionally, the FA-MCC converges at a short time such that theretransmissions performed as a result of the serious interference stillenable the transceiver to forward packets within a predetermined packetdelay. Optionally, the predetermined packet delay variation is shorterthan 100 micro-seconds. Optionally, the second packet loss rate, whichis caused by the serious interference before it is cancelled by the modeconversion canceller, is at least 100, 1,000, 10,000, 100,000 times thefirst packet loss rate. Optionally, the predetermined average rate iscalculated over a window shorter than 1 milli-second. Optionally, theretransmission module comprises a limited-size buffer having capacitysufficient to store all the packets that are transmitted whentransmitting at the highest transmission rate for a period lasting nomore than 40,000 symbols. Optionally, the retransmission modulecomprises a limited-size buffer having capacity sufficient to store allthe packets that are transmitted when transmitting at the highesttransmission rate for a period lasting no more than 5,000 symbols.Optionally, the transceiver and the second transceiver are implementedon integrated circuits having limited resources; and the secondtransceiver comprises a limited-size buffer having capacity sufficientto store all the packets that are transmitted when transmitting at thehighest transmission rate for a period lasting no more than 40,000symbols. Optionally, the FA-MCC is not configured to converge optimally,and does not reach an optimal solution even after 1 second. Optionally,the FA-MCC reduces its ASS, by at least 50%, within less than 50microseconds after it cancels the effect of the serious interference. Inone example, the FA-MCC reduces its ASS, by at least 200%, within lessthan 50 microseconds after it cancels the effect of the seriousinterference. Optionally, the FA-MCC reduces its ASS, by at least 50%,within less than 1 second after it cancels the effect of the seriousinterference. In one example, the FA-MCC reduces its ASS, by at least400%, within less than 1 second after it cancels the effect of theserious interference. Optionally, the FA-MCC reduces its ASS, by atleast 50%, within 1 second from the time the retransmission modulefinishes retransmitting the packets with errors that were lost duringthe time it took the FA-MCC to cancel the effect of the seriousinterference.

In one embodiment, a communication system, having a maximum throughputabove 1.2 Gbit/s, implemented on an integrated circuit (IC) havinglimited resources, includes: a transceiver comprising a digitalcanceller coupled to an Rx analog front end (AFE) and a common modesensor AFE (CMS-AFE) coupled to a differential communication channelthat is coupled to a second transceiver; the differential communicationchannel is not completely known, and the transceiver is expected to workat packet loss below 1% when there is no serious interference; from timeto time the differential communication channel suffers from seriousinterferences that increase the packet loss rate of the transceiver toabove 5%; responsive to receiving an indication that the seriousinterference has occurred, a fast-adaptive mode-conversion canceller(FA-MCC) increases its adaptation step size (ASS) by at least 50% inorder to cancel the effect of the serious interference within less than100 microseconds; and a limited resources retransmission module (LRRM)stores and retransmit an amount of erred packets accumulated during lessthan 100 microseconds at the maximum throughput; wherein the FA-MCCreduces its ASSafter it cancels the effect of the serious interference.

Referring to the embodiment above, optionally, the FA-MCC cancels theeffect of the serious interference within less than 20 microseconds.Optionally, the LRRM stores and retransmit an amount of erred packetsaccumulated during less than 20 microseconds at the maximum throughput.Optionally, the digital canceller feeds a slicer that feeds a PhysicalCoding Sublayer (PCS) with quantization results; the PCS extracts packetdata from the quantization results; and the retransmission modulereceives the packet data, and requests retransmission of packets witherrors based on the packet data. Optionally, the retransmission moduleis implemented on the IC with limited resources that cannot supportretransmission of more than 100% of the packets received during the timeit takes the FA-MCC to cancel the effect of the serious interference.Optionally, the communication system achieves one or more of thefollowing requirements: a maximum allowed jitter, a maximum amount ofdropped packets, and requirements related to time sensitive datatransmitted over the communication channel. Optionally, theretransmission module further comprises a buffer with a capacity that issufficient to store the received packets until all packets are receivedsuccessfully. Optionally, the capacity of the buffer is limited to storeall the packets that are received during up to 20 microseconds while thepacket loss rate is above 5%. Optionally, the FA-MCC is not configuredto converge optimally, and does not reach an optimal solution even after1 second. Optionally, the digital canceller comprises an equalizer and aDecision Based Filter (DBF). Optionally, the equalizer is a Feed ForwardEqualizer (FFE). Optionally, the DBF is a filter fed by the slicer.Optionally, the FA-MCC reduces its adaptation step size by at least 50%within 1 second from the time the retransmission module finishesretransmitting packets with errors that were lost during the time ittook the FA-MCC to cancel the effect of the serious interference.Optionally, the packet data comprises information related to a packetheader, a packet payload, a packet tail, and an error detection code.

In one embodiment, a transceiver combining dynamic coding and fastrecovery, includes: a digital canceller that is coupled to an Rx analogfront end (AFE) and to a common mode sensor AFE (CMS-AFE) that arecoupled to a differential communication channel that is coupled to asecond transceiver; the differential communication channel is notcompletely known and the transceiver is expected to work at a firstpacket loss rate when there is no serious interference; from time totime the differential communication channel suffers from seriousinterferences that increase the packet loss rate of the transceiver to asecond packet loss rate that is at least ten times the first packet lossrate; the digital canceller feeds a slicer that feeds a Physical CodingSublayer (PCS) with quantization results; the PCS extracts the packetsfrom the quantization results; responsive to receiving an indicationthat the serious interference has occurred, a rate controller indicatesthe second transceiver to reduce the code rate of the packets,transmitted over the differential communication channel, by at least50%; the rate controller updates a fast-adaptive mode-conversioncanceller (FA-MCC), the digital canceller and the slicer about thereduction in the code rate; concurrently, the FA-MCC increases itsadaptation step size (ASS) by at least 50% in order to cancel, withinless than 100 microseconds, the effect of the serious interference andto return the transceiver's packet loss rate to the first packet lossrate; and shortly after the FA-MCC cancels the effect of the seriousinterference, the rate controller indicates the second transceiver toincrease the code rate, and updates the FA-MCC, the digital cancellerand the slicer about the increment in the code rate; and the FA-MCCreduces its ASSafter it cancels the effect of the serious interference.

Referring to the embodiment above, optionally, the rate controllerindicates the second transceiver to reduce the code rate of the packetstransmitted over the differential communication channel by 20% to 50%.Optionally, the rate controller indicates the second transceiver toreduce the code rate of the packets transmitted over the differentialcommunication channel by 50% to 95%. Optionally, the FA-MCC utilizeslarge adaptation step size that enables it to cancel, within less than20 microseconds, the effect of the serious interference and to returnthe transceiver's packet loss rate to the first packet loss rate.Optionally, the rate controller indicates the second transceiver tofurther increase the code rate until the second transceiver returns tothe code rate used before the serious interference was detected.Optionally, the transceiver further comprises a retransmission modulethat requests retransmission of packets with errors, based on thepackets extracted by the PCS. Optionally, the retransmission module islimited to support retransmission of up to 200% of the packets receivedduring the time it takes the FA-MCC to cancel the effect of the seriousinterference. Optionally, the transceiver and the second transceiverutilize Dynamic Modulation Coding in order to reduce the code rate.Optionally, the packets are modulated using Pulse-Amplitude Modulation(PAM), and the rate controller commands the second transceiver to switchfrom using PAM16 to PAM4 until the FA-MCC cancels the effect of theserious interference. Optionally, the code rate is reduced by addingError Correction Code to the packets. Optionally, the indication thatthe serious interference has occurred is based on one or more of thefollowing values received from the PCS: a percent of lost packets, arate of lost packets, a function of lost and successfully receivedpackets, a score proportional to the detected interference, a scoreproportional to slicing error provided by the slicer, and a scoreproportional to number of errors detected by the PCS. Optionally, theupdate of the slicer by the rate controller comprises an indication tothe slicer to change its slicer function to a slicing function suitablefor the reduced code rate. Optionally, at least one of the packets thatcould not be sent due to insufficient bandwidth while the code rate wasreduced, is discarded without attempting a delayed transmission orretransmission. Optionally, the packets carry video data, and the atleast one discarded packet comprises video pixel data and does notinclude video controls. Optionally, at least some of the packets thatcould not be sent while the rate was reduced, are stored in a buffer atthe second transceiver, and transmitted after the rate is restored to alevel that permits transmission of the extra data. Optionally, thetraffic transmitted over the differential communication channelcomprises time sensitive data and time insensitive data, and whileoperating in the lower code rate, the second transceiver transmits thetime sensitive data, and stores the time insensitive data in a buffer.Optionally, after cancelling the effect of the serious interference andrestoring the code rate to a level having higher bandwidth, the secondtransceiver transmits the time sensitive data stored in the buffer.Optionally, the FA-MCC reduces the adaptation step size shortly afterthe increase in the code rate. Optionally, the FA-MCC reduces theadaptation step size, by at least 50%, within 1 second from the time ofincreasing the code rate.

In this description, references to “one embodiment” mean that thefeature being referred to may be included in at least one embodiment ofthe invention. Moreover, separate references to “one embodiment” or“some embodiments” in this description do not necessarily refer to thesame embodiment. Additionally, references to “one embodiment” and“another embodiment” may not necessarily refer to different embodiments,but may be terms used, at times, to illustrate different aspects of anembodiment.

The embodiments of the invention may include any variety of combinationsand/or integrations of the features of the embodiments described herein.Although some embodiments may depict serial operations, the embodimentsmay perform certain operations in parallel and/or in different ordersfrom those depicted. Moreover, the use of repeated reference numeralsand/or letters in the text and/or drawings is for the purpose ofsimplicity and clarity and does not in itself dictate a relationshipbetween the various embodiments and/or configurations discussed. Theembodiments are not limited in their applications to the details of theorder or sequence of steps of operation of methods, or to details ofimplementation of devices, set in the description, drawings, orexamples. Moreover, individual blocks illustrated in the figures may befunctional in nature and therefore may not necessarily correspond todiscrete hardware elements.

While the methods disclosed herein have been described and shown withreference to particular steps performed in a particular order, it isunderstood that these steps may be combined, sub-divided, and/orreordered to form an equivalent method without departing from theteachings of the embodiments. Accordingly, unless specifically indicatedherein, the order and grouping of the steps is not a limitation of theembodiments. Furthermore, methods and mechanisms of the embodiments willsometimes be described in singular form for clarity. However, someembodiments may include multiple iterations of a method or multipleinstantiations of a mechanism unless noted otherwise. For example, whena processor is disclosed in one embodiment, the scope of the embodimentis intended to also cover the use of multiple processors. Certainfeatures of the embodiments, which may have been, for clarity, describedin the context of separate embodiments, may also be provided in variouscombinations in a single embodiment. Conversely, various features of theembodiments, which may have been, for brevity, described in the contextof a single embodiment, may also be provided separately or in anysuitable sub-combination. Embodiments described in conjunction withspecific examples are presented by way of example, and not limitation.Moreover, it is evident that many alternatives, modifications, andvariations will be apparent to those skilled in the art. It is to beunderstood that other embodiments may be utilized and structural changesmay be made without departing from the scope of the embodiments.Accordingly, this disclosure is intended to embrace all suchalternatives, modifications, and variations that fall within the spiritand scope of the appended claims and their equivalents.

What is claimed is:
 1. A transceiver configured to recover within lessthan 1 millisecond from quality degradation in its operating point,comprising: a receiver analog front end (Rx AFE), an adaptive modulecomprising at least one of an adaptive digital equalizer and an adaptivedigital canceller (ADEC), and a slicer; the Rx AFE receives a signal ofmore than 500 Mbps from a second transceiver over a link, and feeds thesignal to the ADEC that generates a slicer input signal; the slicerutilizes the slicer input signal to generate slicing decisions andslicing errors; wherein the slicing errors are used to adapt the ADEC;shortly after identifying quality degradation in the transceiver'soperating point, the transceiver indicates the second transceiver totransmitting known data; and within less than 1 millisecond fromidentifying the quality degradation, the transceiver utilizes the knowndata to improve the accuracy of the slicing errors, which enables fastadaptation of the ADEC, that improves the quality in the transceiver'soperating point to a level that enables the transceiver to indicate thesecond transceiver to transmit data.
 2. The transceiver of claim 1,wherein within less than 100 microseconds from identifying the qualitydegradation, the transceiver utilizes the known data to improve qualityin its operating point to a level that enables the transceiver indicatethe second transceiver to transmit data.
 3. The transceiver of claim 1,wherein the link maintains a fixed rate of data transmission, such thatthere is less than 2% difference between a first amount of unique datasuccessfully transmitted over the link over a first 2-millisecond windowthat ends 100 microseconds before identifying the quality degradationand a second amount of unique data successfully transmitted over thelink over a second 2-millisecond window adjacent to the first window. 4.The transceiver of claim 1, wherein the link maintains a fixed rate ofdata transmission, such that there is less than 1% difference between afirst amount of unique data successfully transmitted over the link overa first 500 microseconds window that ends 50 microseconds beforeidentifying the quality degradation and a second amount of unique datasuccessfully transmitted over the link over a second 500 microsecondswindow adjacent to the first window.
 5. The transceiver of claim 4,wherein the quality degradation would have caused a difference above 10%between the amounts of unique data successfully transmitted over the twoadjacent 500 microseconds windows had the transceiver not been recoveredfrom the quality degradation in its operating point.
 6. The transceiverof claim 1, further comprising utilizing retransmission to recover thepackets that were lost from the time of the quality degradation in theoperating point until the time of recovery.
 7. The transceiver of claim1, wherein the link is a differential wired communication link.
 8. Amethod for recovering within less than 1 millisecond from qualitydegradation in a transceiver's operating point, comprising: receiving,by the transceiver, a signal of more than 500 Mbps from a secondtransceiver over a link; feeding the signal to an adaptive modulecomprising at least one of an adaptive digital equalizer and an adaptivedigital canceller (ADEC), for generating a slicer input signal;utilizing the slicer input signal to generate slicing decisions andslicing errors; utilizing the slicing errors for adapting the ADEC;shortly after identifying quality degradation in the transceiver'soperating point, indicating the second transceiver to transmitting knowndata; and within less than 1 millisecond from identifying the qualitydegradation, utilizing the known data to improve the accuracy of theslicing errors, which enables fast adaptation of the ADEC, that improvesthe quality in the transceiver's operating point to a level that enablesthe transceiver to indicate the second transceiver to transmit data. 9.The method of claim 8, wherein within less than 100 microseconds fromidentifying the quality degradation, further comprising utilizing theknown data to improve the quality in the operating point to a level thatenables the transceiver indicate the second transceiver to transmitdata.
 10. The method of claim 8, wherein the link maintains a fixed rateof data transmission, such that there is less than 1% difference betweena first amount of unique data successfully transmitted over the linkover a first 500 microseconds window that ends 50 microseconds beforeidentifying the quality degradation and a second amount of unique datasuccessfully transmitted over the link over a second 500 microsecondswindow adjacent to the first window.
 11. The method of claim 8, furthercomprising utilizing retransmission to recover the packets that werelost from the time of the quality degradation in the operating pointuntil the time of recovery.
 12. A transceiver configured to recoverwithin less than 1 millisecond from quality degradation in its operatingpoint, comprising: a receiver analog front end (Rx AFE), an adaptivemodule comprising at least one of an adaptive digital equalizer and anadaptive digital canceller (ADEC), a common mode sensor AFE (CMS-AFE), afast-adaptive mode-conversion canceller (FA-MCC), and a slicer; the RxAFE receives a signal of more than 500 Mbps from a second transceiverover a differential wired communication link, and feeds the ADEC thatgenerates an equalized signal; the CMS-AFE senses the common mode signalof the differential wired communication link and feeds the FA-MCC thatgenerates a compensation signal; wherein the compensation signal isindicative of differential interference caused by mode-conversion of acommon mode signal; the slicer utilizes the equalized signal and thecompensation signal to generate slicing decisions and slicing errors;wherein the slicing errors are used to adapt the ADEC and the FA-MCC;shortly after identifying quality degradation in the transceiver'soperating point, the transceiver indicates the second transceiver toreduce the rate of the transmitted data in order to improves detectionrate at the transceiver; and within less than 1 millisecond fromidentifying the quality degradation, the transceiver utilizes theimproved detection rate to improve the accuracy of the slicing errors,which enables fast adaptation of the ADEC, that improves the quality inthe transceiver's operating point to a level that enables thetransceiver to indicate the second transceiver to increase the rate. 13.The transceiver of claim 12, further comprising utilizing the slicingdecisions to adapt the ADEC and the FA-MCC.
 14. The transceiver of claim12, wherein the quality degradation in the transceiver's operating pointis quality degradation in the slicer input signal, which causes errorsin slicing decisions above a predetermined threshold.
 15. Thetransceiver of claim 12, wherein the quality degradation in thetransceiver's operating point is quality degradation in the slicingerrors, which are indicative of the detection quality of thetransceiver.
 16. The transceiver of claim 12, wherein within less than100 microseconds from identifying the quality degradation, thetransceiver utilizes the reduced rate to improve quality in itsoperating point to a level that enables the transceiver indicate thesecond transceiver to transmit data.
 17. The transceiver of claim 12,wherein the link maintains a fixed rate of data transmission, such thatthere is less than 2% difference between a first amount of unique datasuccessfully transmitted over the link over a first 2-millisecond windowthat ends 100 microseconds before identifying the quality degradationand a second amount of unique data successfully transmitted over thelink over a second 2-millisecond window adjacent to the first window.18. The transceiver of claim 12, further comprising utilizingretransmission to recover the packets that were lost from the time ofthe quality degradation in the operating point until the time ofrecovery.
 19. The transceiver of claim 12, wherein the FA-MCC isimplemented as part of the ADEC.
 20. A method for recovering within lessthan 1 millisecond from quality degradation in a transceiver's operatingpoint, comprising: a receiver analog front end (Rx AFE), an adaptivemodule comprising at least one of an adaptive digital equalizer and anadaptive digital canceller (ADEC), a common mode sensor AFE (CMS-AFE), afast-adaptive mode-conversion canceller (FA-MCC), and a slicer;receiving, by the transceiver, a signal of more than 500 Mbps from asecond transceiver over a differential wired communication link; feedingthe signal to an adaptive module comprising at least one of an adaptivedigital equalizer and an adaptive digital canceller (ADEC), forgenerating an equalized signal; sensing the common mode signal of thedifferential wired communication link; feeing the sensed signal to afast-adaptive mode-conversion canceller (FA-MCC) that generates acompensation signal; wherein the compensation signal is indicative ofdifferential interference caused by mode-conversion of a common modesignal; utilizing the equalized signal and the compensation signal forgenerating slicing decisions and slicing errors; utilizing the slicingerrors for adapting the ADEC and the FA-MCC; shortly after identifyingquality degradation in the transceiver's operating point, indicating thesecond transceiver to reduce the rate of the transmitted data in orderto improves detection rate at the transceiver; and within less than 1millisecond from identifying the quality degradation, utilizing theimproved detection rate to improve the accuracy of the slicing errors,which enables fast adaptation of the ADEC, that improves the quality inthe transceiver's operating point to a level that enables thetransceiver to indicate the second transceiver to increase the rate. 21.The method of claim 20, wherein within less than 100 microseconds fromidentifying the quality degradation, further comprising utilizing thereduced rate to improve the quality in the operating point to a levelthat enables the transceiver indicate the second transceiver to transmitdata.
 22. The method of claim 20, wherein the link maintains a fixedrate of data transmission, such that there is less than 2% differencebetween a first amount of unique data successfully transmitted over thelink over a first 2-millisecond window that ends 100 microseconds beforeidentifying the quality degradation and a second amount of unique datasuccessfully transmitted over the link over a second 2-millisecondwindow adjacent to the first window.
 23. The method of claim 20, whereinthe link maintains a fixed rate of data transmission, such that there isless than 1% difference between a first amount of unique datasuccessfully transmitted over the link over a first 500 microsecondswindow that ends 50 microseconds before identifying the qualitydegradation and a second amount of unique data successfully transmittedover the link over a second 500 microseconds window adjacent to thefirst window.
 24. The method of claim 20, further comprising utilizingretransmission to recover the packets that were lost from the time ofthe quality degradation in the operating point until the time ofrecovery.